[OSM-talk] Proposal for import guidelines

Eric Marsden eric.marsden at free.fr
Tue Sep 25 22:36:51 BST 2012


Thank you for making this constructive proposal. My feeling is that it
would constitute a positive change to the current DWG import guidelines,
which are greatly lacking in subtlety. 

Allow me to point out, and illustrate with the French cadastre case, a
problem posed by the wish strictly to separate the "import" component of
a bulk edit (corrected/checked building geometries) from the
"integration" component (resolving conflicts with existing building
geometries and their tags, improving highway geometries using the high
resolution cadastre information, etc.). Under the current (French)
community guidelines for integrating this data, these two steps are
combined in a single changeset. Separating them would lead to a
situation where, during the period between these two changesets, the
database is in an inconsistent state (overlapping buildings, highways
passing through buildings, etc.).

Whilst this temporary inconsistency in the data is not as severe as it
would be in a software development project, for instance (the dreaded
FTBFS), it is rather dirty and could lead to false alerts in error
checking software.

Whether this data consistency problem is more or less significant than
the improved tracability of data source copyright that is afforded by
the proposed import/integration separation is debatable. In my view, the
costs of the proposed change outweigh its benefits (at least as far as
the French cadastre situation is concerned -- other bulk edits/imports
will likely have different tradeoffs). 

-- 
Eric Marsden




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